moparman13045

I am having a bit of trouble and I am not sure what is wrong. So the truck is an 04.5 auto, mostly stock, just a smarty (sw2) and edge ez (level 2). All of a sudden, one day the truck began to start funny. You would go out to fire it up and it would crank a little longer than normal, then fire up. Once it fired up, I noticed that for about 5 seconds, it runs a little rough, and puffs a little white smoke. Then it smooths right out and runs good. It usually does it worse when its colder out, or the longer the truck has been shut off. One day when I was driving around town, the truck acted like it was going to quit for a second (rail pressure dropped for a split second), but then regained itself. It has never happened again.

I have a quadzilla commander monitor that I have been monitoring fuel pressures, egt, rail pressure, etc with. Anyhow, lately it looks as if I have been showing a bit lower fuel pressure than normal (normally about 9 psi at idle, now its ~8 or ~7, but at cruising speed 5-6, sometimes going down hills it reads higher, or when you hit the brakes hard), about the same time I had some of the starting troubles.
I tried a new fuel filter, and at the same time I filled up my diesel tank, put a double dose of Power Service cleaner in. Seemed to help slightly but its still there.

Next I checked for codes, no codes at all. I searched the forums and checked my rail pressure at startup, seems to be around 5k psi, but I am not 100% certain because it starts up so fast that I can't see the reading.

I have been checking my dipstick everyday, no extra oil at all (went 600 miles this past weekend).

Today I checked exhaust manifold temps right at the outlet, with an infrared laser heat gun, put it on the flanges, showed good for each cylinder, all around 152-165* at idle, with the #5 at around 170. I think this is normal though.

I don't know what to do now, I should probably plug off the rail relief valve and see if that works, but I am not sure what size bolt that is exactly. Anyone have any suggestions? Thanks in advance.

ratlratl

You are describing one of the incidents with my last '03 to a "T". Turns out it was the FCA. After keeping the truck on two occassions for three days at a time, that's what the dealer came up with. I was told the ECM was setting the target pressure but the FCA wasn't responding. I was running the Sick-Gun on that truck so I took it off. Problem was still there. Fixed FCA and didn't have trouble after that.

Chris

Super Googan

What is the FCA?

Rpainter

fuel control activator it si bolted to the back of the cp3

moparman13045

Is there anyway to test the FCA by any chance? I am kinda of glad to here that the preliminary response is not a bad injector, as I think these get replaced sometimes when they don't need to be. Thanks alot,

gatf4

Exact same symptoms on my truck fixed last week after replacing the fuel rail pressure sensor.

kinghomes

My dealer mechanic is trying to decide if my stall problem is FCA , rail p. or ECM or wire. He really does not know. he is double checking wires now. I don't believ he has good technique for diagnosing which part has failed. The only thing I have seen on this forum is the guy that read a high rail p. at key on not turning starter. He was using a hand scanner to read. Figure rail p. needs to turn to build p. so should read 0 or atleast as low as low p side at key to on no starter turn. try to check that.

Other wise I hope to hear how you find your problem

Try cleaning your floor mats.

moparman13045

I think I might try and take out the FCA and clean it to see if it might help, make sure it is moving freely in the bore, etc. My truck is over 100k (120k) so it is out of factory warranty. I will let you guys know how I make out. Thanks alot, Justin

moparman13045

Okay so I took out the FCA took it apart, and cleaned it. It did not look too bad inside. It seemed to move in and out of the bore well. I took a few pics if anyone wants to see them. The only advice I would have on the FCA is that when you reassemble it, carefully put the little cap that holds the spring in there. It can easily go past its spot, as there is no machined stop for it.

Next, I took out the pressure relief valve, it looked quite dirty inside actually compared to everything else, I have no idea if it was working right or not, but I cleaned it anyhow because its easy to do. I noticed that when you look inside it, it looks as if it can be taken apart/adjusted, as there is a helicoil type thing in it, then an allen head spring stop inside. I took some pics.

Overall, I have no idea if it helped yet, I will find out tomorrow morning when I go to start it.

ollie32

I'm interested to know what your finding are? I have the same problem. I am leaning more towards the preheat coil, simply because it is harder to start in cooler temperatures. If I plug the truck in all night it fires up no problem. When the truck is cool the voltage guage seems to be low and the lights dim on and off. This has lead me to believe the preheat grid is drawing alot of amp. Once you drive for a while, obviously when the engine has warmed up the voltage goes up to around 15 in the normal range.
I am curious to here if this makes any difference, I was chasing a fuel snag for a while but never did anything. I am waiting for a new pre heat grid, will see what happens.

tbarbee1

Did it start????

cwoodall

Moparman..........you have us all chomping at the bit. So you say your CR Pressure Relief Valve looked dirty inside? If it can be cleaned/rehabilitated, that's a $400 savings in itself!! Good work man......

tbarbee1

Did it start????

moparman13045

Hey guys, the truck has started perfect this morning after sitting all night, but it was quite warm (air temp) last night, and then again today after work. I noticed that it fired up with less time than before and ran perfectly smooth, no rough idle, zero smoke. I don't want to say its solved yet and jinx it though. I will let you know how it starts tomorrow morning.

moparman13045

ollie32
My trucks lights dim a little bit when its colder out and the amp gauge goes down quite a bit then bounces back up, then repeats the cycle several times until the truck is warmed up. Yours could be drawing too many amps though, I just don't know how you would test it.

cwoodall
That pressure relief valve I belief could be disassembled. I am not sure whats inside, but if you know how to remove helicoils, then you could take it apart. The helicoil stops the little spring stop inside from being removed which would then allow you to remove the internal parts. I don't know how you remove helicoils though.
What I should have done is seperately cleaned the FCA, then tried the truck, then, if that didn't work, tried the pressure relief valve, that way I would know which one that I cleaned helped the situation.

I will keep you guys updated though.